Sputter coated glass articles are known in the art. For example, see U.S. Pat. Nos. 5,770,321, 5,298,048, and 5,403,458, each of which disclose coatings sputtered onto substrates and corresponding techniques for the same, all of these patents being hereby incorporated herein by reference. Sputter coated layer systems on glass substrates are typically used for achieving solar management properties (e.g., low emissivity or low-E, UV reflection, and/or the like) in different types of glass articles including but not limited to insulating glass (IG) window units, vehicle windows (e.g., windshields, backlites, sidelites, sunroofs), and/or the like.
Sputter coating may be an electric discharge process, often conducted in a vacuum chamber in the presence of one or more gases. An example sputter coating apparatus typically includes at least one vacuum chamber in which a substrate is located in a stationary or moving fashion, a power source, an anode, and one or more specifically prepared cathode targets of or covered with at least one material (e.g., silicon, zinc, silver, nickel, chrome, tin, aluminum, other materials, or combinations thereof) to be used in creating a layer(s) on the substrate. When an electric potential is applied to the cathode target, the gas(es) (e.g., argon, nitrogen, oxygen, other gases, or combinations thereof) form(s) a plasma that bombards the target causing particles of the coating material to be liberated or lifted from the target itself. The liberated coating material from the target falls onto the underlying substrate and adheres thereto. When conducted in the presence of a reactive gas(es), a reactive product of the coating material from the target and the gas may be deposited on the substrate (e.g., in forming a silicon nitride layer).
For example and without limitation, see FIG. 1 which illustrates a conventional sputter coating apparatus. The apparatus includes six different zones (i.e., zones 1–6) which are separated from one another by curtains or walls 52. Zone 1 includes targets 21–26, zone 2 includes targets 27–29, zone 3 includes targets 30–35, zone 4 includes targets 36–41, zone 5 includes targets 42–44, and zone 6 includes targets 46–50. The sputtering targets may be any suitable type of target including but not limited to planar targets, rotating cylindrical targets, magnetron targets, and/or C-Mag targets. In the example of FIG. 1, targets 27–29 and 42–44 are planar targets, while targets 21–26, 30–41, and 45–50 are rotating cylindrical targets. At least one gas (e.g., argon, nitrogen, oxygen, etc.) may be utilized in each zone at low pressure (i.e., pressure below atmospheric), while vacuum pumps 51 are provided between zones in order to try to reduce the amount of crosstalk (i.e., in order to reduce the amount of gas from one zone leaking into an adjacent zone). A glass substrate is passed through the sputter coater (e.g., at line speed of from 100–300 inches per minute) in order to be coated. For purposes of example and without limitation, a multi-layered solar control coating can be deposited onto the substrate using this sputter coating apparatus as explained in more detail in U.S. Pat. No. 6,336,999, the disclosure of which is hereby incorporated herein by reference.
Other types of sputtering systems/techniques are disclosed in U.S. Pat. Nos. 5,968,328, 5,399,252, 5,262,032, 5,215,638, 6,203,677, 6,207,028, and 5,403,458, and WO 02/04375 (see U.S. Ser. No. 09/794,224), all of which are hereby incorporated herein by reference.
Other example types of sputtering system are known as ion beam assisted sputtering system which utilize an ion beam(s) to help liberate coating material form a target(s). Sputtering devices of this type may be found, for example and without limitation, in any of U.S. Pat. Nos. 6,197,164, 6,296,741, or 6,214,183, all of which are hereby incorporated herein by reference.
Unfortunately, each of the aforesaid sputtering devices are problematic in that they can only coat one side of a substrate at a time. This is undesirable, at least from a processing time and capital expenditure perspective, in situations where it is desired to coat both sides of a substrate. Accordingly, it can be seen that there exists a need in the art for an apparatus which is capable of coating both sides of a substrate without necessarily having to pass the substrate through the apparatus more than one time.